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Biomedical subjects

S Yoshida

Publications and source records attributed to S Yoshida.

At least 19 recordsLinked to original sources
PubMed1992

Regulatory effects of platelet-derived growth factor-AA homodimer on migration of vascular smooth muscle cells.

Migration of medial smooth muscle cells (SMC) into the intima is important in intimal thickening of atherosclerotic tissues. To study the functions of three isoforms of platelet-derived growth factor (PDGF) in atherosclerosis, we investigated their effects on SMC migration by Boyden's chamber method. Although PDGF-AB and PDGF-BB enhanced SMC migration dose-dependently, PDGF-AA did not enhance SMC migration, but instead inhibited SMC migration induced by PDGF-AB or PDGF-BB. PDGF-AA also inhibited SMC migration induced by two other migration factors, fibronectin and SMC-derived migration factor. PDGF-AA is considered to be coexpressed with transforming growth factor (TGF)-beta 1 in atherosclerotic tissues. Treatment of SMC with TGF-beta 1 reduced an autocrine migration activity from SMC. Studies using anti-PDGF antibody revealed that an increased secretion of PDGF-AA by TGF-beta 1 caused the reduced migration activity. cAMP increase by forskolin and dibutyryl cAMP suppressed SMC migration, whereas cAMP decrease by pertussis toxin had no effects on PDGF-AA-suppressed migration. In contrast, staurosporine, an inhibitor of protein kinase C, enhanced SMC migration and neutralized the inhibitory effect of PDGF-AA. These findings suggest that PDGF-AA regulates SMC migration in intimal thickening in atheroma formation and that protein kinase C may play an important role in the inhibitory mechanism of PDGF-AA.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

RFP is a DNA binding protein associated with the nuclear matrix.

We reported that the RFP gene encodes a protein with putative zinc finger domains and was involved in the activation of the ret proto-oncogene. To further characterize the RFP protein, we developed a polyclonal antibody against the product synthesized from a fragment of the RFP cDNA expressed in Escherichia coli. Western blot analysis showed that RFP was identified as a 58 kDa protein in cell lysates from four human and rodent cell lines and from mouse testis. In addition, a unique 68 kDa protein was detected in the testis. Using AH7974 (rat ascites hepatoma) and Raji (human Burkitt lymphoma) cells, we demonstrated strong association of RFP with the nuclear matrix. Furthermore, RFP solubilized from the nuclear matrix had DNA-binding activity although it appears to bind more preferentially to double-stranded DNA than to single-stranded DNA. These results thus suggest that RFP may play a role in molecular processes which occur in the nuclear matrix.

Amino Acid Sequence↗
PubMed1992

Inhibition of eukaryotic DNA polymerase alpha with a novel lysophosphatidic acid (PHYLPA) isolated from myxoamoebae of Physarum polycephalum.

A specific inhibitor of DNA polymerase alpha was isolated from the lipid fraction prepared from myxoamoebae of a true slime mold, Physarum polycephalum. The purified substance was subjected to structural studies by fast atom bombardment mass spectroscopy, infrared spectroscopy, and two-dimensional nuclear magnetic resonance spectroscopy. The structure of this substance was thereby suggested to be a novel lysophosphatidic acid (LPA) composed of cyclic phosphate and cyclopropane-containing hexadecanoic acid. Then we named this substance PHYLPA (Physarum LPA). PHYLPA inhibited more than 80% of the affinity-purified calf thymus DNA polymerase alpha activity at a concentration of 10 micrograms/ml (approximately 20 microM). Inhibition was observed for DNA polymerase alpha but not for DNA polymerase beta or gamma from various eukaryotic species, nor did it inhibit DNA polymerase I from E. coli. From kinetic analyses, the inhibition was considered to be caused by the interaction of PHYLPA with the template DNA.

Animals↗
PubMed1992

A one-step sandwich enzyme immunoassay for human matrix metalloproteinase 3 (stromelysin-1) using monoclonal antibodies.

A one-step sandwich enzyme immunoassay (EIA) for matrix metalloproteinase 3 (MMP-3; stromelysin-1) was developed. The assay system used two simultaneous immunoreactions using a solid phase monoclonal antibody and a horseradish peroxidase-labeled monoclonal antibody (Fab'). The sensitivity of the assay system was 20 micrograms/l and linearity was obtained between 31 and 500 micrograms/l. The EIA system was capable of measuring both precursor and active forms of MMP-3 as well as the forms of MMP-3 complexed with tissue inhibitors of metalloproteinases. MMP-3 levels as measured by this assay are significantly higher in the sera of patients with rheumatoid arthritis as compared to those of healthy subjects and patients with osteoarthritis. Immunoblot analyses showed that in the sera and synovial fluids of patients with rheumatoid arthritis, MMP-3 is present in the 59- and 57-kDa precursor forms.

Animals↗
PubMed1992

Efficient purification of a full length and biochemically active p110Rb, the retinoblastoma gene product.

Rb protein was purified from recombinant baculovirus-infected Sf9 cells to apparent homogeneity by a simple solubilization and by immunoaffinity column chromatography. It was mainly obtained as p110Rb, the underphosphorylated form of the Rb protein family. This p110Rb was shown to form a specific complex in vitro with SV40 Tag and to bind to double or single stranded DNA. It could also affect Tag helicase activity in a biphasic-dose dependent manner, due to these two biochemical functions. This purification procedure provides sufficient amounts of native Rb protein to further elucidate its role as an anti-oncogene protein and a negative regulator of the cell cycle.

Animals↗
PubMed1992

[A study of irradiated spines in radiotherapy--using 99mTc-HMDP bone scintigraphy & MR imaging].

When radiation therapy is performed on a patient with malignant tumor, vertebral spines are sometimes included in the irradiation field. In the present study, 99mTc-HMDP uptake was examined in 102 cases of malignant tumors treated with radiation therapy (irradiated total doses from 10 to 70 Gy) in order to clarify the time course of accumulation. The scintigram on the film was transformed with a film digitizer into objective data, and the Accumulation Decreasing Index (ADI) was calculated each month after irradiation. In the group receiving less than 30 Gy, recovery of 99mTc-HMDP accumulation was seen after a mild decrease in the ADI. However, in the group that received more than 40 Gy, no recovery of accumulation was seen, and a large decrease in the ADI followed. Vertebral MRI was performed with and without Gd-DTPA enhancement to calculate the vertebral Signal Intensity Ratio (SIR), and decreased blood flow in the irradiated bone marrow was estimated from the changes in SIR values. In the irradiated area, no definite abnormal accumulation of 99mTc-HMDP was observed against the new metastatic bone tumor. In such cases, MRI should be performed soon after bone scintigraphy in order to detect the tumor.

Bone Marrow↗
PubMed1992

Anticardiolipin antibodies in NZW x BXSB F1 mice. A model of antiphospholipid syndrome.

NZW x BXSB F1 (W/B F1) male mice develop systemic lupus-like disease, and several autoantibodies, circulating immune complexes, and lupus nephritis become apparent. The abnormally high incidence of degenerative coronary vascular disease with myocardial infarction and thrombocytopenia due to the presence of both platelet-associated antibodies and circulating antiplatelet antibodies in this animal has been reported. We found that W/B F1 male mice produced autoantibodies against cardiolipin (aCL) and that the titer of aCL increases with age. aCL from W/B F1 male mice were mainly IgG and binding activity to cardiolipin was aCL-cofactor (beta 2-glycoprotein I (beta 2-GPI)) dependent. We developed monoclonal aCL from these animals and examined specificity of the autoantibodies. All the mAb used reacted with the negatively charged phospholipids, cardiolipin, phosphatidylserine, and phosphatidylinositol, and some reacted with platelets and DNA. The addition of human or mouse beta 2-GPI enhanced the titer for monoclonal aCL from the W/B F1 mice. From the results of competitive inhibition enzyme immunoassay with monoclonal aCL and purified beta 2-GPI, aCL from the W/B F1 mice recognized the complex of CL and beta 2-GPI. The W/B F1 male mouse may be an appropriate model for use in studies on the pathologic significance of aCL in patients with antiphospholipid syndrome.

Animals↗
PubMed1992

Localization of basic fibroblast growth factor-like immunoreactivity in the rat brain.

The immunohistochemical localization of basic fibroblast growth factor (bFGF) was studied in the adult rat brain, using a specific antibody against a synthetic bFGF fragment (the N-terminal 12 residues). Widespread but uneven regional localization of bFGF-like immunoreactive neurons and fibers was observed. Ependymal cells were also stained. The immunoreactive neurons were found in the cerebral cortex, olfactory bulb, septum, basal magnocellular nuclei, thalamus, hypothalamus, globus pallidus, hippocampus, amygdala, red nucleus, central gray of the midbrain, cerebellum, dorsal tegmental area, reticular formation, cranial motor nuclei and spinal cord. Immunoreactive fiber bundles and nerve terminals were also detected. These results indicate that bFGF is produced by or present in a specific neuronal cell population of the central nervous system.

Amino Acid Sequence↗
PubMed1992

Alterations in biodistribution of 11C-methamphetamine (MAP), 14C-MAP, and 123I-N-isopropyl-iodoamphetamine (IMP) in MAP- and cocaine-sensitized animals.

Alterations in brain distribution of 11C-MAP, 14C-MAP, and 123I-IMP in MAP- and cocaine-sensitized animals were examined to investigate the mechanism involved in increased dopaminergic transmission and behavioral sensitization. First, a significant increase in 11C-MAP radioactivity in the striatum and hypothalamus was found in the mice pretreated with MAP for 7 days. Secondly, in MAP-sensitized rats, marked increases in 14C-MAP radioactivity were found in the striatum and limbic forebrain, respectively (370% and 650%). These findings may propose a new hypothesis that subchronic MAP administration may result in a long-term change in the presynaptic cell membrane at the nerve terminal which may in turn cause an increase in both MAP and DA uptake accompanied by an increased release of DA at the synaptic cleft.

Amphetamines↗
PubMed1992

Hyaluronate synthesized by cultured skin fibroblasts derived from patients with Werner's syndrome.

Hyaluronate in cultured skin fibroblasts derived from patients with Werner's syndrome, who excrete large amounts of urinary hyaluronate, was investigated. The amount of hyaluronate secreted into the medium by Werner's fibroblasts was 2-3-times that of normal fibroblasts, whereas no difference in enzyme activities related to the degradation of hyaluronate was found. Werner's fibroblasts were then cultured in the presence of [3H]glucosamine, and the amount of [3H]hyaluronate and its chain lengths in the medium and matrix (trypsinate) fractions were compared with those of normal cells. No significant difference in the chain length of hyaluronate was observed between normal and Werner's fibroblasts. On the other hand, a significant increase of hyaluronate was found in the matrix fraction of Werner's fibroblasts when the cells reached confluency. In addition, a hyaluronate of small chain length was found in the matrix fraction of Werner's fibroblasts, although this was absent from that of normal cells. It was concluded that the constituents of the extracellular matrix of Werner's fibroblasts differed from those of normal cells, characterized by the presence of a large amount of hyaluronate and a relatively small hyaluronate chain.

Adult↗
PubMed1992

Moderate oxidation of hypertriglyceridemic low-density lipoprotein causes apolipoprotein B epitope change and enhances its uptake by macrophages.

We prepared monoclonal antibody (MabB4) that selectively binds to acetylated low-density lipoprotein (LDL). Native hypertriglyceridemic LDL (HT-LDL) obtained from IIb and native normotriglyceridemic LDL (NT-LDL) from type IIa scarcely bound with MabB4. When these LDL were oxidized moderately by incubation with copper ions, the binding of MabB4 to HT-LDL was enhanced compared to that of NT-LDL, although the contents of the hydroperoxide they produced were the same. The incorporation of moderately oxidized HT-LDL into macrophages was enhanced compared to that of NT-LDL, and the rate of incorporation parallel the binding of LDL for MabB4. These results suggested that moderate oxidation of HT-LDL expressed some apolipoprotein B epitope on the surface of acetylated LDL to a much greater degree than NT-LDL, and that this expressed epitope might work as a ligand of moderately oxidized HT-LDL for the recognition by macrophages.

Apolipoproteins B↗
PubMed1992

[An experimental and clinical study of zonography of the lung by means of Fuji computed radiography].

Tomography was conducted for a basic study using a model of the bronchi, pulmonary arteries and veins. When the exposure angle of a tube was changed to 5, 10, 25, and 50 degrees, the width of tomograms became about 10, 4, 2, and 1 cm. When tomograms of exposure angles of 50 degrees and 10 degrees were compared, the former showed fragmentary bronchi, pulmonary arteries and veins, and the latter showed bronchi, pulmonary arteries and veins branching up, down and laterally on one image in one unit and over a wide area. Similar results were obtained in 10 cases of normal volunteer. When 25 cases of lung cancer at the hilum were studied clinically with respect to bronchial lesions, the tomograms with an exposure angle of 10 degrees could point out more lesions than the tomograms with an exposure angle of 50 degrees. In 13 cases (40 lesions) which were compared with the findings of bronchoscopy, the accuracy was only 25% in tomograms with an exposure angle of 50 degrees, and 65% in tomograms with an exposure angle of 10 degrees. These results indicate that tomograms with an exposure angle of 10 degrees are useful for analysis of the bronchi, pulmonary arteries and veins at the hilum of the lung.

Adenocarcinoma↗
PubMed1992

Effects of NIK-247 on CO-induced impairment of passive avoidance in mice.

The effect of NIK-247 on carbon monoxide (CO)-induced amnesia were investigated. A step-down type passive avoidance task with mice was used to compare the effects of NIK-247 with those of tacrine. Two types of CO-induced amnesia model, acute and delayed models, were used. The acute amnesia model was developed using mice exposed to CO before memory consolidation, just after training, and a retention test carried out 24 h after training. The delayed amnesia model was prepared 7 days after CO exposure even when the animals were exposed to CO 4 h after training, after memory had consolidated. NIK-247 administered post-training at 0.03-0.3 and 3 mg/kg or pre-retention test (24 h after training) at 0.3 and 10 mg/kg attenuated the acute amnesia. In addition, NIK-247 (0.03, 0.1, 1 and 10 mg/kg) and tacrine (0.03, 0.1 and 1 mg/kg) administered before the retention test (7 days after CO exposure) improved retrieval in the delayed amnesia model. Tacrine (0.01-0.3 and 3 mg/kg), administered post-training, attenuated the acute amnesia but pre-retention test administration did not. The dose-response curves for NIK-247 and tacrine were biphasic bell-shaped. These results indicated that NIK-247 has an improving effect on hypoxia-induced acute and delayed cognitive dysfunction, and suggest that NIK-247 has promise as a nootropic drug for therapy of memory deficits in patients with cerebrovascular-type dementing disorders.

Aminoquinolines↗
PubMed1992

Effects of substitutions of glycine and asparagine for serine132 on activity and binding of human lipoprotein lipase to very low density lipoproteins.

For studying the role of Ser132 in the putative catalytic site of human lipoprotein lipase (LPL), mutant LPL cDNAs expressing LPLs with amino acid substitutions of Gly or Asn for Ser132 were obtained by site-directed mutagenesis, and were expressed in COS-1 cells. Considerable amounts of LPL enzyme protein mass were detected in the culture medium of COS-1 cells transfected with wild-type LPL, LPL-Gly132, or LPL-Asn132. LPL-Gly132 hydrolyzed Triton X-100-triolein and tributyrin as effectively as wild-type LPL, whereas LPL-Asn132 showed no activity. LPL-Asn132 bound to very low density lipoproteins as effectively as wild-type LPL.

Amino Acid Sequence↗
PubMed1992

Condensation activity for polyunsaturated fatty acids with malonyl-CoA in rat brain microsomes. Characteristics and developmental change.

Condensation activities for gamma-linolenic acid (18:3(n-6)), octadecatetraenoic acid (18:4(n-3)) and eicosapentaenoic acid (20:5(n-3)) with malonyl-CoA were measured and compared with the condensation activities for 16:0-CoA, 18:1-CoA, 18:2(n-6)-CoA and 18:3(n-3)-CoA in rat brain microsomes of various ages. The age-dependence of condensation activities for 18:3(n-6), 18:4(n-3) and 20:5(n-3) showed a maximum at 1- to 2-month-old and were still higher at 3-month-old 2- to 3-fold than the activities in microsomes of pups. Conversely, the age-dependence of condensation activity for 16:0-CoA showed a peak around 1 month-old, but decreased at 3-month-old to the level of the activities in pups. The condensation activity for 20:5(n-3) was inhibited by 18:3(n-6) or 18:4(n-3) and the inhibition was not competitive. The condensation of 18:3(n-6) was also inhibited by 18:4(n-3) in the same manner. A physiological implication of the inhibition system at the substrate level was discussed.

Animals↗
PubMed1992

A heterozygous mutation (the codon for Ser447----a stop codon) in lipoprotein lipase contributes to a defect in lipid interface recognition in a case with type I hyperlipidemia.

Previously, we reported a case with type I hyperlipidemia due to a lipid interface recognition deficiency in lipoprotein lipase (LPL) (1). The LPL from postheparin plasma of this patient did not hydrolyze TritonX-100-triolein or very low density lipoprotein-triolein but did hydrolyze tributyrin and LysoPC-triolein substrates. Sequence analysis of the probands DNA revealed a heterozygous nucleotide change: a C----G transversion at position of 1595, resulting in changing the codon for Ser447 to a stop codon. Expression studies of this mutant LPLcDNA in Cos-1 cells produced and secreted considerable amounts of LPL mass in the culture media. The mutated LPL hydrolyzed much less TritonX-100-triolein than wild type LPL, whereas hydrolysis of tributyrin and LysoPC--triolein was the same with both the mutant and wild type LPL. These results suggest that this mutation might be responsible for the property of the LPL with a defect in lipid interface recognition in the type I patient we reported.

Adipose Tissue↗
PubMed1992

Epoxyeicosatrienoic acid stimulates ADP-ribosylation of a 52 kDa protein in rat liver cytosol.

In rat liver cytosol, rapid ADP-ribosylation of a 52 kDa protein by endogenous ADP-ribosyltransferase(s) was observed. This ADP-ribosylation was stimulated dose-dependently by 14,15-epoxyeicosatrienoic acid (14,15-EET), one of the metabolites of arachidonic acid by NADPH-dependent cytochrome P-450 mono-oxygenase. This stimulatory effect required the presence of GTP or its non-hydrolysable analogues, guanosine 5'-[beta gamma-imido]triphosphate or guanosine 5'-[gamma-thio]triphosphate. Of four regioisomeric EETs, 14,15-EET was the most potent. No stimulatory effect was observed with addition of 14,15-dihydroxyeicosatrienoic acid, a stable metabolite of 14,15-EET. The 52 kDa protein was not ADP-ribosylated by cholera toxin A subunit and pertussis toxin, and was not recognized by anti-Gs alpha and anti-Gi alpha antibodies. However, the 52 kDa protein could be photoaffinity-labelled with 8-azidoguanosine 5'-[alpha-32P]triphosphate. These results suggest that the 52 kDa protein is neither Gs nor Gi, though it may have a GTP-binding site. These results contribute to the understanding of the role of mono-oxygenase metabolites of arachidonic acid in intracellular signal transduction.

8,11,14-Eicosatrienoic Acid↗